Recently, there has been a growing interest in new and renewable energy due to a global environmental issue, for example, depletion of fossil energy, waste disposal of nuclear power generation, and site selection for construction of new power plants, and the like. Most of all, research and development in the field of solar energy generation, that is, a non-polluting energy source, is actively conducted worldwide. The amount of energy that the earth receives from the sun is about 10,000 times more than the amount of energy consumption in the earth.
Solar cells are devices for directly converting solar photovoltaic energy into electrical energy. The solar cells have difficulties in commercialization due to their economic feasibility. To replace traditional generation means such as fossil energy and the like, the solar energy needs to be more economical or be economically competitive than the traditional generation means. Thus, techniques relating to solar energy are being focused on the increase of generation efficiency as well as the improvement of economic feasibility.
Moreover, to manufacture such solar cells, a circuit needs to be formed on a wafer substrate. Techniques for forming the circuit can be largely divided into a screen printing method and a plating method. The screen printing method is a printing method using silver paste. However, as silver (Ag) increases in price, price competitiveness of products may be low, and also, electrical conductivity may be deteriorated due to impurities such as binder and glass bid led that constituting silver paste. Thus, there is a limitation in efficiency of electricity conversion. As a result, technologies using plating are being actively carried out in the recent years.